 /*******************************************************************************
  * Copyright (c) 2007 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  ******************************************************************************/

 package org.eclipse.ui.menus;

 import org.eclipse.jface.resource.ImageDescriptor;
 import org.eclipse.ui.IWorkbench;
 import org.eclipse.ui.IWorkbenchPartSite;
 import org.eclipse.ui.IWorkbenchWindow;
 import org.eclipse.ui.services.IServiceLocator;

 /**
  * Allow a command or application to provide feedback to a user through updating
  * a MenuItem or ToolItem. Initially used to update properties for UI elements
  * created by the CommandContributionItem.
  * <p>
  * This class may be extended by clients.
  * </p>
  *
  * @since 3.3
  */
 public abstract class UIElement {

     private IServiceLocator serviceLocator;

     /**
      * Construct a new instance of this class keyed off of the provided service
      * locator.
      *
      * @param serviceLocator
      * the locator. May not be <code>null</code>.
      */
     protected UIElement(IServiceLocator serviceLocator)
             throws IllegalArgumentException {
         if (serviceLocator == null)
             throw new IllegalArgumentException ();
         this.serviceLocator = serviceLocator;
     }

     /**
      * Update the label on this UI element.
      *
      * @param text
      * The new label to display.
      */
     public abstract void setText(String text);

     /**
      * Update the tooltip on this UI element. Tooltips are currently only valid
      * for toolbar contributions.
      *
      * @param text
      * The new tooltip to display.
      */
     public abstract void setTooltip(String text);

     /**
      * Update the icon on this UI element.
      *
      * @param desc
      * The descriptor for the new icon to display.
      */
     public abstract void setIcon(ImageDescriptor desc);

     /**
      * Update the disabled icon on this UI element.
      *
      * @param desc
      * The descriptor for the new icon to display.
      */
     public abstract void setDisabledIcon(ImageDescriptor desc);

     /**
      * Update the hover icon on this UI element.
      *
      * @param desc
      * The descriptor for the new icon to display.
      */
     public abstract void setHoverIcon(ImageDescriptor desc);

     /**
      * Update the checked state on this UI element. For example, if this was a
      * toggle or radio button.
      *
      * @param checked
      * true to set toggle on
      */
     public abstract void setChecked(boolean checked);

     /**
      * Get the service locator scope in which this UI element resides. May not
      * be <code>null</code>.
      *
      * <p>
      * The locator may be used to obtain services that are scoped in the same
      * way as the {@link UIElement}. Such services include but are not limited
      * to {@link IWorkbench}, {@link IWorkbenchWindow}, and
      * {@link IWorkbenchPartSite}. While this method may not return
      * <code>null</code> requests for any of these particular services may
      * return <code>null</code>.
      * </p>
      *
      * @return the service locator for this element
      * @see IServiceLocator#getService(Class)
      */
     public final IServiceLocator getServiceLocator() {
         return serviceLocator;
     }

     /**
      * Set the menu contribution id to use. This is only applicable to menu
      * contributions that support a drop-down style menu. The default
      * implementation does nothing.
      * <p>
      * Example: element.setDropdownId("org.eclipse.ui.navigate.back.my.menu");
      * </p>
      *
      * @param id
      * used to populate the dropdown menu. Must not be
      * <code>null</code>.
      */
     public void setDropDownId(String id) {
         // This does nothing.
 }
 }

